Assertion: pendulum clocks go slow in summer and fast in winter.

Reason: The length of the pendulum used in the clock increases in summer.

Assertion: A simple pendulum is mounted on a truck that moves with constant velocity The time period of the pendulum will increase.

Reason: The effective length of the pendulum will decrease.

Assertion: SHM is not a periodic motion.

Reason: Periodic motion does not repeat its position after a certain interval of time.

Assertion: When a particle is at an extreme position performing SHM, its momentum is equal to zero.

Reason: At the extreme position, the velocity of a particle performing SHM is equal to zero.

Assertion: In a compound pendulum, if the suspension point and centre of oscillation are mutually interchanged, then no change in a time period is obtained.

Reason: Length of the equivalent simple pendulum remains same in both the case.

Assertion: In SHM, the motion is to and fro and periodic.

Reason: Velocity of the particle, $v=\omega \sqrt{a^2-x^2}$ (where $x$ is displacement)